Abrasive blast machine



June 18, 1940. v

E. R. HUGHES 2,204,596v

ABRASIVE BLAST "ACHINE Filbd April 25-, 1938 2 Sheets-Sheet 2 INVENTOREdward 252159711 BY I ATTO R N EY l Patented June 18, 1940 ABRA SIVEBLAST Edward R. Hughes, Morristown, N. 1., asaignor to The AmericanFoundry Equipment Company, Mishawaka, Ind., a corporation of DelawareApplication April 26, 1938, Serial No. 264,268

8 Claims.

\ 5 ings, bars, sheets and like material.

In accordance with this invention, the metallic shot, grit, sand orsimilar cleaning agent, is projected against the article to be cleanedby means of a rapidly rotating throwing wheel having 10 blades orthrowing elements radially mounted thereon. The blades and other wearingparts may be made removable and replaceable. The abrasive is fed intothe path of the rotating blades near the axis of rotation of the wheel35 where the peripheral velocityis relatively low.

In order to bring the abrasive under directional control so thatsubstantially all, if not all, the abrasive is thrown in the desireddirection, it is necessary that the abrasive be deposited upon theadvancing face of the throwing blades during the rotation of the bladesthrough a predetermined limited arc. A serious defect of abrasivethrowing wheels, such as illustrated in the Beeg United States PatentNo. 554,473, Young 8; Conley United States Patent No. 859,863, and Weber8.: Grocholl German Patent No. 539,056, is lack of substantialdirectional control of the thrown abrasive due to the fact that theblades have a tendency to spatter the abrasive in all directions and theabrasiveis not deposited suitably upon the advancing face of the bladeswhen rotating through a limited arc. As a result the abrasive is thrownin all directions resulting in serious damage and destruction to thesurrounding shroud or guard and to other parts of the equipment.

In accordance with this invention the abrasive is conducted onto theblades at the inner portions thereof at a substantial initial velocitywhich approaches the peripheral speed of rotation of the blades at thepoint where the abrasive passes onto the face of theblades. The abrasivemay be given this initial velocity in any desired and convenient manner,but preferably by subjecting the abrasive to pressure so as to cause arapid, controlled, flow of the abrasive.

Propulsion of the abrasive onto the face of the blades may be effectedby providing a gravity fiow supplemented and aided by pressure devices,such as airblast pressure. The blade edge over which the abrasive flowsis also reduced to a relatively thin edge so that the blade itselfoffers the least possible obstruction to the entry of the abrasive ontothe face of the blade. Means are also provided for adjusting theposition of the feed device throwing blade;

in various clock-dial positions to effect the desired direction ofdischarge of abrasive from the wheel.

An object of this invention is to provide a centrifugal abrasiveblasting machine wherein a high degree of directional control of thethrown abrasive is accomplished.

Another object of this invention is to provide an improved centrifugalwheel and abrasive feed assembly whereby the abrasive can be depositedonto the advancing face of the throwing blades over a limitedpredetermined arc with a minimum amount of diffusion or scattering ofthe abrasive.

Other objects of this invention will become apparent as the disclosureproceeds.

Various other features andadvantages of the 15 invention. will beapparent from the following particular description and from aninspection of the accompanying drawings.

Although the novel features which are believed to be characteristic ofthis invention will be particularly pointed out in the claims appendedhereto, the invention itself, as to its objects and advantages, and themanner in which it may be carried out, may be better understood byreferring to the following description taken in connection with theaccompanying drawings forming a part thereof, in which Fig. 1 is a sideelevational view of my improved centrifugal blasting machine showingmore particularly an abrasive throwing wheel and abrasive 30 feedingdevice associated therewith;

Fig. 2 is a transverse cross-sectional view of my improved centrifugalblasting machine showing more particularly certain structural detailsthereof, this view being taken on line 2--2 of 35 Fig. 1;

Fig. 3 is a top plan view of my centrifugal blasting machine;

Fig. 4 is an enlarged perspective view of a Fig. 5 is a longitudinalcross-sectional view through a centrifugal blasting machine of somewhatmodified construction, this view being taken on line 5-5 of Fig. 6;

Fig. 6 is a transverse cross-sectional view of the modified centrifugalblast machineillustrated in Fig. 5, this view being taken on line 6-6 ofFig. 5: and I v Fig. 7 is an enlarged perspective view of an abrasivethrowing blade and mounting therefor used in the wheel illustrated inFigs. 5 and 6.

In the following description and in the claims, various details will beidentified by specific names for convenience, but they are intended tobe as generic in their application as the art will permit. u

Like reference characters denote like parts in the several flguresof thedrawings.

The centrifugal blast machine as illustrated in Figs. 1 to 4, inclusive,comprises more particularly a rotor including a rotatable disc or a sidewall member I, fixed to a rotatably mounted drive shaft 2 by means of ahub 3 secured to the side wall I as by bolts I. The hub 3 is sultablysecured against rotation on the shaft 2, as by a spline (not shown).

A plurality of blades 49, illustrated as four in number, are mountedupon the disc 5, preferably in such a manner as to permit removal andreplacement thereof. It is understood 'at two or more blades can be usedin the rotor here disclosed. To permit satisfactory feeding, it ispreferable to limit the rotor to not more than eight blades.

The throwing blades d9 may'be shaped as illustrated more particularly inFigs. 2, 3 and l, each blade comprising more particularly a blade wall50, an outer flange portion ti, and an inner flange portion 52. Theinner end of the blade d9 may be formed with a curvature, as illustratedin the drawings, to facilitate the reception of abrasive on theadvancing face of the -of the blade wall 50. The smoothly curved flanges5| and 52 facilitate the smooth and uniform flow of the abrasive in itspassage over the face of the blades.

The throwing blades 49 may be removably held in fixed position on theside wall I in a suitable manner, as for example, by screws I.Preferably,

each blade 49 is provided with a lug extending from the inner sideflange 52 at'the portion of the blade which lies against the side wallI. A center block 5 of generally peaked shape is disposed centrally ofthe rotor and secured to the side plate I as by screws 4. Preferably,the center block 5 is adapted to provide a support for the curvedtapered inner end portions of, the throwing blades and also may serve toguide abrasive onto the rotating throwing blades l 9.'

The abrasive is fed into the path of the throwing blades 49 through afeed conduit I which extends in a suitable direction. The feed conduit15 comprises a reduced throat IG-and a feed nozzle H, the end of whichextends to closely adjacent the path of rotation of the reduced endportions53 of the blades 49. The abrasive is supplied to the conduit l5through a suitable feed pipe I8, which extends into, the conduit Ii asubstantial distance, and preferably is spaced therefrom to provide anair space .20 therebetween.

Centrifugal abrasive throwing wheels to effectively clean hard metalliccastings, should develop a peripheral tip blade velocity of 110,000 to15,000 lineal feet per minute. If a rotor having a diameter of 18 inchesis used, for example, the

'. rotor must be rotated from 2200 to 2800 R. P. M.

to develop this peripheral velocity. when the rotor is rotating at thishigh speed, it will be appreciated that the abrasive must be projectedonto the face of the blade at a velocity which approaches the speed oftravel of the blade at that point if substantial spattering andscattering of the abrasive are to be avoided. This is accomplished bysubjecting the abrasive flowing through the nozzle portion ll of thefeed conduit l5 to an acceleration 'suflicient to cause the abrasive tobe ejected from the feedopening II at a velocity whichapproaches theperipheral velocity of the reduced edge portion 53 of the blade wherethe abrasive passes onto the leading face of the blade, or which may beslightly greater.

In the form shown in Fig. 2, for example, an

accelerating force may be applied to the abrasive by providing an airjet nozzle or inlet 22 positioned with its outlet at approximately thejunction of the throat It and feed nozzle I! of the feed conduit andpositioned to eject air in the general direction of the length of thenozzle I! and in a sense toward the discharge outlet l9.

Air under pressure is introduced into the jet nozzle 32 and flowsthrough the nozzle H in the general direction of travel of abrasiveflowing through the feed-pipe it. This not only accelerates the abrasiveand-hurls it through the dis-' charge opening HQ with the desiredvelocity, but also serves to prevent any clogging or arcing of abrasivein the feed conduit 95 particularly at the juncture of the throat l6 andfeed nozzle II. It will be noted that the discharge outlet I! of the fedconduit is positioned relatively close to the axis of rotation of therotor. It will be appreciated that it is desirable to position thedischarge outlet IQ of the feed conduit relatively close to the axis ofrotation of the rotor where the veloclty of the blade surface isrelatively low,

and yet offset radially and entirely on one side,

of the axis, so as to confine the abrasive feed to a limited arc of thepath of rotation of the inner portions of the blades.

The discharge outlet I9 isnot only offset radially from the axis ofrotation of the rotor but the direction of discharge of abrasive fromthe discharge outlet is inclined to the radii of the rotor in a sense inthe direction of rotation of the rotor. Thus, the abrasive is deliveredinto the path of the blades in a generally outward direction with avelocity which has a component the abrasive is deposited on the leadingfaces of the blades with a minimum of shock. Thus turbulence andbounding of abrasive is minimized. and a more smooth and even'flow ofabrasive along the faces of the blades is insured.

The throat ii of the feed conduit is preferably mounted so that it maybe adjusted to various constant, the abrasive stream may be thrown.

radially of the rotor and also a component in the direction of rotationof the blades, whereby clockedial positions whereby direction ofabrasive discharged from the rotor can be adjusted.

Thus, by a proper adjustment of the discharge either downward, orupward, or to either sideof the rotor.

The nozzle may be adjustably mounted by a rotatably mounted plate 30supported upon 9.

suitable bracket 25 fixed to a stationary support 26 as by means ofbolts 21. A collar portion 3| provided on the rear of the circular plate30 is received in a circular opening cut in the bracket 25, and ashoulder portion 32 on the clrcular plate 30 abuts the outside face ofthe inner circular rim portion II of the bracket. The circular plate 30is held in rotatable position by the provision of a suitable rim membera which overlaps the inside face of the rim portion 28 of the bracketand is secured in position by screws 34 extending through the shoulderportion 3| of the rotatable plate 30. The throat portion I6 preferablyextends through a bushing mem ber 35 which seats within a circularopening provided in the rotatable plate 30. The bushing 35 may beprovided with shoulders 36 and 31 which surround the circular edge ofthe opening in the circular plate 30.

It will be noted that the bushing 35 is positioned so as to support thedischarge opening I! of the feeding device in an off-center position andclosely adjacent to the path of the thinned edge portions 53 of theblades. appreciated that when the circular plate 30 is rotated, thedischarge opening II of the feed device may be brought into andpositively held in any desired clock-dial position with respect to theaxis of rotation of the rotor. Where the feed conduit is to be adjustedto certain positions, a suitably shaped feed conduit is substituted forthe feed conduit shown in order to eliminate the necessity for feedingupwardly into the throat portion.

As illustrated more particularly in Figs. 1 to 3 the bracket 25 may beprovided with a laterally projecting rim portion 38 which surrounds theperipheral edge of the circular disc 30. Suitably spaced notches 39 maybe cut in the rim portion 38' to receive a spring-pressed plunger bolt40 which is slidably supported in a suitable sleeve 4I fixed to orformed integral with the rotatable plate 30. The plunger bolt 40 slidingwithin the sleeve 4I is provided with a reduced shaft portion 42 whichterminates in a head 43 by which the plunger bolt 40 may be manipulated.A compression spring 44 surrounding the stem 42 and abutting against theshoulder 45 provided on the draw-bolt 40 and a shoulder 48 provided onthe interior of the sleeve 4I automatically retains the draw-bolt 40 incooperative seating engagement with a selected notch 39 in the rimportion 38. l

By exerting an outward pull on the head portion 43 the bolt 40 may bewithdrawn from the notch in which it is seated, permitting rotation ofthe circular plate 30 so as to bring the discharge opening I! of thefeeding device into the desired clock-dial position. It will beappreciated that other means may be provided for permitting rotatableadjustment of the discharge opening ll of the feeding device within thepurview of this invention.

The inventive concept represented by the present invention is capable ofvarious embodiments, and a second embodiment of the invention isillustrated in Figs. 5 to 7. This apparatus includes a rotor I00comprising a balanced side wall I M mounted on a shaft I02 for rotation,by a hub I03, the side wall being suitably secured to the hub as bybolts I04. -The hub I03 is secured against rotation on the shaft in asuitable manner, as by a spline (not shown).

Carried on the side .wall member MI is a plurality of spaced throwingblades I05 which extend in a general direction inwardly from adjacentthe periphery of the rotor I00'toward the axis of rotation thereof..Each blade comprises a relatively straight member having a body portionorwall IIO, abase III and a base flange H2. The base flange II2preferably is of dovetail construction adapted to engage withcorrespondingly shaped edge portions II6 of wear plates II5 which aregenerally segmental in It will thus be shape. A suitable number of wearplates III are provided in accordance with the number of blades and aresecured to the side wall member IOI in a suitable manner, as by boltsIII.

The side edge of each blade I05 preferably Is provided with a flange I20on the leading face of the blade, which'flange extends from the outerend of the blade to a point short of the inner end. The edge portion ofthe blade I05, extending from the inner end of the flange I20 to theinner end of the blade is provided with a taper or bevel as indicated atI 2|, whereby this side edge portion of the blade is of reducedthickness, for a purpose which will hereinafter appear.

For the. purpose of feeding abrasive into the path of rotation of theblades I05, a feed conduit I25 is provided. The feed pipe I25 includes athroat or pipe portion I26 which preferably extends downwardly and anozzle I2'I which extends toward the rotor IOI and in a directiongenerally outwardly of the rotor. The nozzle I 21 has a discharge outletI28 located adjacent the path of rotation of the inner side edgeportions of the blades, as illustrated particularly in Fig. 6. Abrasiveis delivered to the feed conduit I25 in any suitable manner by a pipe orconduit" I29. Preferably the conduit I29 is readily removable from thefeed pipe I25 or is readily movable therewith in order to permitadjustment of the feed pipe I25 as hereinafter described.

For the purpose of accelerating abrasive flowing in the feed conduit I25and discharging it from the discharge outlet I28 with the desiredvelocity, an air jet nozzle or inlet I30 is provided in the feed conduitI25. The air jet nozzle or inlet I30 is so located and directed that theair jet is pointed in the direction of the discharge outlet I28 andimparts a velocity to the abrasive in this direction. The air jet nozzleI30 is located at the juncture of the throat I26 and the nozzle I21 andthus serves not only to impart a velocity to the abrasive in the desireddirection, but also prevents clogging or choking of the feed conduit.

The feed .pipe l 25 is suitably mounted relative to the rotor I00 in afirm and rigid manner so that it is retained in suitable operatingposition. Furthermore, the feed conduit I 25 is mounted so that theclock-dial position of the discharge outlet I28 can be adjustedrelatively to the axis of the rotor.

The mounting means may be constructed in a manner generally similar tothe mounting means illustrated in Figs. 1 to 3, inclusive, and describedin detail above. It is also advisable in this embodiment to provide oneor more additional feed conduits of different suitable shapes to besubstituted accordingly where the same is to be adjusted to certainpositions.

A circular plate I40 is mounted in -a bracket I for turning movementabout the axis of the rotor I00. The plate I40 may be secured in thebracket MI by a rim member I42 and may be locked in the desired positionby a locking mechanism (not shown) generally similar to that illustratedin Figs. 1 to 3 and described in the accomdischarge outlet I28isradially oflset from the axis of rotation of the rotor and is locatedclosely adjacent the path of rotation of the reduced edge portions I22of the blades. The nozzle I21 is so positioned that it directs a streamof abrasive into the path of rotation of the bladesin a directioninclined to the radii of the rotor in the sense of rotation of therotor. Thus, abrasive is thrown into the path of the throwing bladeswith a velocity having a component radially of the rotor and a componentin the direction of rotation of the blades. I

Since the abrasive is given an initial velocity in the direction ofrotation of the blades, it is de- .of bounding and turbulence.

posited on the leading faces of the blades with a minimum of shock andthus is forced outwardly by the'rotating throwing blades with a minimumThis not only results in a more desirable action of the throwing wheel,but also minimizes wear of the throwing blades and deterioration of theabrasive particles.

Since the edge portion I22 of each throwing blade across which theabrasive is delivered by the feed pipe I25 is reduced in thickness,there is a minimum obstruction to and interference with the passage orabrasive onto the leadin faces of the throwing blades with the resultthat the spread and direction of the abrasive hurled by the throwingblades can be more accurately controlled. Furthermore, since there is aminimum of interference with the passage of abrasive onto the throwingblades, only a very small portion of the abrasive is diverted and thrownout of the path of the throwing blades.

While certain novel features of the invention have been disclosedherein, and are pointed out in the annexed claims, it will be understoodthat various omissions, substitutions and changes may "be made by thoseskilled in the art without departing from the spirit of the invention.

What is claimed is: 1. An abrasive throwing machine comprising a rotorincluding a plurality of spaced throwing blades, means mounting saidblades for rotation,

and means for feeding abrasive into the path of rotation of said blades,said feeding means including a conduit having a portion extendingdownwardly and a nozzle portion extending in a direction generallytoward and outwardly of said rotor, said nozzle portion having adischarge outlet disposed adjacent the inner portions of the blades at alocation. offset radially from the axis of rotation of said rotor andpositioned to deliver abrasive in a direction crossing the radii of therotor in the direction of rotation of .the rotor, and means in saidconduit foraccelerating abrasive whereby abrasiveis discharged into thepath Y of rotation of said blades with a velocity outwardly of saidrotor and in the direction of rotation of said blades. o

2. An abrasive throwing machine comprising a rotor including a pluralityof spaced throwing 'blades extending inwardly from adjacent theperiphery of said rotor'toward the axis of rotation and having thinnededges at their inner portions and means mounting said blades forrotation,

, and means for feeding abrasive into the path of rotation of saidblades, said feeding means including a conduit having a portionextending down- ,wa'rdly and a nozzle portion extending in a directiongenerally toward and outwardly of said rotor, said. nozzle having adischarge outlet disposed adjacent the path of the thinned edge portionsof the blades and at a location offset radially from the axis ofrotation of said rotor and positioned to deliver abrasive in a streamcrossing the radii of the rotor in the general direction of rotation Ior the rotor, and means in said conduit for accelthe rotor, and meansfor feeding abrasive into the path of rotation of said blades, saidfeeding means comprising a conduit having a discharge outlet adjacentthe path of rotation of the inner portions of said blades and offsetradially from the axis of rotation of the rotor, said conduit beingpositioned to direct abrasive outwardlyof the rotor and in the generaldirection of rotation of said rotor, and means comprising an air let foraccelerating abrasive in said conduit.

4. A machine for throwing abrasive at blasting velocities comprising arotor including a side wall member, a plurality of spaced throwingblades carried by said side wall member and extending inwardly fromadjacent the periphery oi the rotor toward the axis of rotation, andmeans for feeding abrasive into the path of rotation of said blades,said feeding means comprising a conduit having a discharge outletadjacent the path of rotation of the side edges of said blades andoffset radially from the axis of rotation of the rotor,

, said conduit being positioned to direct abrasive a rotor including aplurality of spaced throwing blades and means mounting said blades forrotation, and means for feeding abrasive into the path of rotation ofsaid blades, said feeding means including a conduit having a portionextending downwardly and a nozzle portion extending in a directiongenerally toward and outwardly of said rotor, said nozzle portion havinga discharge outlet disposed adjacent the inner portions of the blades-ata location offset radially from the axis of rotation of said rotor andpositioned to discharge abrasive in a stream crossing the radii of therotor and in the general direction of the rotation of the rotor, andmeans including an air inlet in said conduit adjacent the juncture ofsaid downwardly extending portion and said nozzle portion fordischarging abrasive from said discharge outlet whereby abrasive isdischarged into the path of rotation of said blades with a velocityoutwardly of said rotor and in the direction of rotation of said blades.

6. An abrasive throwing machine comprising a rotor including a pluralityof spaced throwing blades, means mounting said blades for rotation, andmeans for feeding abrasive into the path of rotation of said blades,said feeding means-inblades at a location offset radially from the' axisof rotation of said rotor and positioned. to deliver abrasive in adirection crossing the radii of the rotor in the general direction ofrotation of the rotor, means in said conduit for accelerating abrasivewhereby abrasive is discharged into the path of rotation of said bladeswith a velocity outwardly of said rotor and in the direction of rotationor said blades, and means rigidly mounting said conduit adjacent saidrotor for angular adjustment of said conduit whereby the clockdialposition of said discharge outlet can be adjusted relatively to the axisof rotation of said rotor.

7. An abrasive throwing machine comprising a rotorv including aplurality of spaced throwing blades extending inwardly from adjacent theperiphery of said rotor toward the axis of rotation and having theirinner edge portions of reduced thickness and means mounting said bladesfor rotation, and means for feeding abrasive into the path of rotationof said blades, said feeding means including a conduit having anabrasive supply portion and anozzle portion extending in a directiongenerally toward and outwardly of said rotor, said nozzle portion havinga discharge outlet disposed adjacent the path of rotation of the inneredge portions of the blades and at a location ofiset radially from theaxis 0'! rotation of said rotor, said feeding means being positioned todeliver abrasive in a stream crossing the radii of the rotor inthegeneral direction of rotationof the rotor, and meansfor dischargingabrasive from said discharge outlet into the path of rotation of saidblades with avelocity in the direction of rotation of said blades.

8. A machine for throwing abrasive at blasting velocities comprising arotor including a side wall member, a'plurality of spaced throwingblades carried by said side wall member and extending inwardly fromadjacent the periphery of the rotor toward the axis of rotatiomand meansfor feeding abrasive, into the path of rotation of said blades. saidfeeding means comprising aconduit having a discharge outlet adjacent thepathrof rotation of the side edges of said blades, each of said bladeshaving a side edge portion or reduced thickness across which abrasive isfed by said feeding means and a side flange portion extending from saidside edge portion to the outer end of said blade, each of said flangeportions being offset radially from the axis of rotation of A the rotor,said conduit being positioned to direct abrasive ina direction outwardlyof the rotor and crossing the radii of the rotor in the generaldirection of rotation of said rotor, and means for accelerating abrasivein said conduit. p

, EDWARD R. HUGHES.

